MULTI-PLACE COATING APPARATUS AND PROCESS FOR PLASMA COATING

Abstract

The invention relates to a coating apparatus (1) for the plasma coating of workpieces (25, 27), comprising a reactor (18) with a sleeve part (19) and a base element (33), with at least one sealed coating chamber (15, 17) being defined between the sleeve part (19) and base element (33), the latter two parts are in the fitted-together condition, and a device (2) for introducing electromagnetic energy into the at least one coating chamber (15, 17). The reactor (18) has at least two coating places (12, 14), and in that the sleeve part is moveable.

Full Text

Multi-place coating apparatus and process for plasma coating
Description
The invention relates to a coating apparatus and to a process
for the plasma coating of workpieces, in particular a coating
apparatus having a plurality of coating places and a process
for the simultaneous coating of a plurality of workpieces.
The barrier properties of plastic containers, such as for
example plastic bottles can be improved considerably by
barrier layers on the inner surface or outer surface of such
containers. It is in this way possible, for example, to
protect foodstuffs from the effects of oxygen, which is
relatively good at diffusing through most types of plastics.
Coatings of this type can be deposited on the container
walls, inter alia by means of various CVD processes (CVD:
chemical vapor deposition). For this purpose, the plasma is
generally ignited at a low pressure in a gas atmosphere which
includes a precursor gas. The reaction products formed in the
plasma are then deposited as a coating on the workpiece to be
treated. The low-pressure atmosphere required to ignite the
plasma needs the area surrounding the workpiece to be
evacuated. This can be done, for example, by suitable lock
means or also by the workpiece being introduced into the
reactor space under standard pressure and the reactor space
then being evacuated. The way in which the workpiece is
transferred from a standard pressure atmosphere to a low-
pressure atmosphere or a vacuum is accordingly a key problem
with regard to the process speed and costs for a CVD coating.
WO 01/31680 A1 has disclosed an apparatus for the low-pressure plasma
treatment of containers in which the treatment station includes a stationary
cavity which can be closed and opened by means of a removable cover, the
cover having a connecting passage which, in the closed state of the treatment
station, produces a connection to a vacuum circuit. The containers which are to
be coated are inserted into the stationary cavity and then the cover is closed,
after which the cavity can be evacuated.
However, this design is disadvantageous in that the container which is to be
coated has to be conveyed into the cavity along two mutually perpendicular
directions, which involves a complicated movement. Moreover, when inside the
cavity the container is surrounded on all sides, apart from the opening which is
covered by the cover in the closed state, by the walls of the cavity and is
therefore difficult to grip after coating has taken place in order to be conveyed
onward. Furthermore, the throughput which can be achieved through an
apparatus of this type is limited, since the sequence of movements has to be
repeated for each individual container for each coating operation.
Therefore, the invention is based on the subject of providing a coating apparatus
and a process which simplify the conveying of workpieces out of and into the
coating reactor and allow a high throughout to be achieved. This object is
achieved in a surprisingly simple way by a coating apparatus, a coating
installation, and a process for the plasma coating of workpieces according to the
features of the invention.
Accordingly, a coating apparatus according to the invention,
or a plasma station for the plasma coating of workpieces,
comprises,
a reactor or a plasma chamber with a moveable sleeve
part and a base element, with at least one sealed coating
chamber or cavity being defined or formed between sleeve part
and base element in the position in which they are fitted
together, and
a device for introducing electromagnetic energy into the
at least one coating chamber. Moreover, the reactor has at
least two coating places. The result of this is that at least
two workpieces can be supplied, coated and removed again
simultaneously. The arrangement according to the invention
with a moveable sleeve part facilitates the sequence of
movements for insertion and removal of the workpieces.
The process according to the invention for the plasma coating
of workpieces, which can be carried out in particular in an
apparatus according to the invention having a reactor with a
moveable sleeve part and a base element, accordingly provides
for
at least two workpieces which are to be coated to be
arranged on the base element,
the sleeve part to be fitted together with the base
element through movement of the sleeve part, so that in the
fitted-together position at least one sealed coating chamber
is defined or formed between sleeve part and base element, in
which coating chamber at least one of the workpieces is
located,
the coating chamber to be evacuated,
process gas to be introduced, and
a plasma to be generated by the introduction of
electromagnetic energy.
On account of the fact that the coating operation is carried
out for two or more workpieces simultaneously, the throughput
can be increased by a corresponding factor by the apparatus.
Since the sleeve part is designed to be moveable with respect
to a stationary base element, the coating places for the
workpieces are readily accessible. On account of the moveable
sleeve part, the workpieces do not have to be introduced into
the sleeve part, but rather can simply be arranged at or on
the base element, with the sleeve part then being fitted over
the workpieces during the closing movement.
Moreover, the invention allows a coating apparatus with low
moving masses to be designed, since only the sleeve part has
to be moved.
To open and close the coating chamber, the sleeve part can
advantageously be moved substantially perpendicular to the
base element by means of a corresponding guidance of the
sleeve part in order to make the coating places as freely
accessible as possible.
According to one embodiment of the invention, the base
element is in the form of a base plate.
Moreover, it is particularly advantageous if the base element
has supply passages through which operating media are
provided. In this context, the provision of operating media
comprises in particular the evacuation and/or venting and/or
supplying of process gas through the supply passages. Since
the base element remains stationary with respect to the
coating apparatus when the reactor is being opened and
closed, it is in this way possible to virtually avoid dynamic
or moving vacuum connections, such as for example corrugated
hoses, and moving seals. In particular this arrangement
allows a robust, low-maintenance design with few moving
parts. Moreover, it is in this way possible for valves which
are used to control and switch the incoming flows of gases
and for discharge purposes, to be arranged directly on or in
the vicinity of the base element and in the vicinity of the
coating chambers. The result is a low dead volume.
According to a first embodiment, at least two separate
coating chambers are defined between sleeve part and base
element. The use of separate coating chambers means that the
plasmas ignited in the individual coating places cannot
influence and interfere with one another.
However, according to a further embodiment of the invention,
it is also possible to provide a common coating chamber for
at least two coating places. This may be advantageous, for
example, if the workpieces are coated in a common plasma.
The device for introducing electromagnetic energy preferably
has at least one supply conductor which passes the
electromagnetic fields into the coating chamber. This supply
conductor may, for example, engage in an opening in the
sleeve part. To seal the opening, the edge of the latter
and/or the conductor, for example at a sealing collar, may be
provided with a seal.
Microwaves or radio-frequency fields are generally used to
ignite and maintain the plasma. To enable these waves to be
transported, the at least one supply conductor preferably
comprises a waveguide and/or a coaxial conductor.
To open and close the coating chamber, the sleeve part may
advantageously be configured such that it can move along the
supply conductor(s), or for the opening and closing can be
moved along the supply conductor for supplying
electromagnetic energy. In this way, the supply conductor can
simultaneously serve as a guide for the sleeve part.
Furthermore, the device for introducing electromagnetic
energy may preferably, moreover, comprise at least one device
for generating electromagnetic energy. The fields used to
generate the plasma are therefore generated directly in the
coating apparatus, and consequently there is no need for
microwaves or radio-frequency waves to be supplied, which
under certain circumstances would have to be effected by
means of flexible conductors which are difficult to handle.
This is advantageous in particular if the coating apparatus
is moved on a conveyor device of a coating installation or of
a plasma module.
It is preferable for the introduction of electromagnetic
energy to comprise the introduction of microwaves in order to
allow large quantities of energy to be introduced into the
plasma. For this purpose, the device for generating
electromagnetic energy may advantageously comprise at least
one microwave head. The latter may, for example, have a
magnetron as microwave source. A frequency of 2.45 GHz is
particularly suitable for the microwaves generated by the
microwave head.
Moreover, the device for introducing electromagnetic energy
may advantageously also comprise a device for distributing
the electromagnetic energy, for example in the form of a
waveguide or impedance structure. The energy generated by a
source can be distributed to a plurality of coating places or
coating chambers using a device of this type. A device of
this type may, for example, comprise a waveguide or impedance
structure as described in the earlier German patent
application bearing the application number 101 38 693.1-52,
the content of disclosure of which is hereby incorporated in
full by reference in the subject matter of the present
application.
In a preferred embodiment of the invention, a pulsed plasma
is generated by the supply of pulsed electromagnetic energy.
Accordingly, in this embodiment of the invention, the device
for generating electromagnetic energy comprises a device for
generating pulsed electromagnetic energy. A pulsed plasma for
applying the pulse induced CVD or PICVD process (PICVD =
pulse induced chemical vapor deposition) as coating process
is generated by means of pulsed electromagnetic energy. The
PICVD process is therefore advantageous compared to plasma-
enhanced chemical vapor deposition (PECVD), in which the
plasma is maintained continuously, inter alia because this
process allows the heating of the temperature-sensitive
plastics to be reduced. Moreover, gas exchange is possible
during the times outside the pulses, in which no plasma is
excited. This leads to particularly pure layers, since
undesired reaction products can be discharged in the
intervals between pulses and new precursor gas can be
supplied.
One main application of the apparatus according to the
invention is for the coating of workpieces which are in the
form of hollow bodies, for which purpose the coating places
may advantageously be designed to receive workpieces of this
type. The coating places may in particular be designed to
receive bottles, ampoules, spherical caps or light bulb
bodies. However, coating of solid bodies, such as for example
solid plastic moldings, is also possible using the coating
apparatus.
One embodiment of the invention provides for the evacuation
of the coating chamber to be carried out in steps in at least
two pressure stages. This has proven expedient for a rapid
evacuation operation, since it makes the evacuation in the
individual pressure stages more efficient.
The apparatus according to the invention may in particular
also be designed for the internal coating of workpieces which
are in the form of hollow bodies. Accordingly, following the
evacuation, process gas is introduced into the interior, so
that when electromagnetic energy is supplied or radiated in,
a plasma is ignited there and a coating is deposited on the
inner walls of the workpieces. In this context, it is also
advantageous if the coating places have seals for sealing off
the interior of the workpieces in the form of hollow bodies.
Sealing off the interior from the area surrounding the hollow
bodies creates the option of providing different atmospheres
and/or pressures in the interior of the workpieces and the
area surrounding them. By way of example, the area
surrounding the workpiece and the interior of the workpiece
can be evacuated simultaneously, the interior being evacuated
down to a base pressure, typically
in the range from 0.05 to 0.8 mbar, and the area surrounding
the workpiece being evacuated either i) likewise to below the
base pressure or ii) to a fixed external pressure in the
range from 1 to 100 mbar, in particular in the range from 10
to 100 mbar.
Then, by way of example, process gas can be introduced into
the interior. For purely internal coating, accordingly,
process gas is supplied only to the interior. In this way it
is possible, for example, to generate a plasma selectively
only in the interior, since the gas density in the
surrounding area is insufficient to form a plasma.
To enable separately controllable atmospheric conditions of
this type to be created, it is advantageous if, for example,
the base element has separate supply passages for evacuating
and/or venting and/or supplying process gas for the interior
of and the area surrounding the workpieces in the form of
hollow bodies. By way of example, it is also possible for the
supply passages of two or more coating places to be connected
to one another via common further supply passages or supply
lines. This reduces the effective overall length and wall
surface area of the supply passages and thereby increases the
pumping power and the gas flow.
It is also expedient for the gas flow, in this case
specifically for the flow of process gas, if process gas is
supplied or introduced into a coating chamber via at least
one gas lance. The gas lance may be arranged in such a way
that its one or more openings are located in the plasma. In
this way, the transport paths for the precursor gas in the
plasma are kept short, so that it is distributed as uniformly
as possible within the shortest possible time.
The gas lance may be designed such that it can be moved in
and out. This is useful, for example, for internal coatings
of hollow bodies, when the gas lance projects into the
interior of the workpiece in the form of a hollow body, and
would therefore constitute an obstacle during introduction or
removal of the workpiece. In this case, the gas lance can be
withdrawn from the interior of the workpiece prior to the
latter being removed and can then be introduced into a
further workpiece again after the latter has been inserted.
The movement of the gas lance and in particular also of the
sleeve part can be imparted in a particularly simple way by
means of mechanical control cams. These cams may be arranged
at a coating installation and, by way of example, can impart
the movement of sleeve part and/or gas lance via cam rollers
arranged thereon. Moreover, the control of the opening and
closing operation of a coating reactor with mechanical
control cams, as well as further design details, are
described extensively in the German application bearing
application number 102 28 898.4, the content of disclosure of
which is hereby incorporated in full by reference in the
subject matter of the present application.
An economical coating process requires high-performance
installations. To achieve a high performance in an
installation of this type, it is particularly expedient if
the coating region of the coating chamber can be evacuated to
the required or desired final pressure as quickly as
possible. For this purpose, it is expedient if the feed lines
to the coating chamber have good conductances.
Furthermore, it is expedient if the feed lines to the coating
chamber produce only small volumes which additionally have to
be evacuated. Therefore, it is within the scope of the
invention to provide a process and an apparatus which allow
an increased throughput.
For this purpose, the invention provides a coating
installation for the vacuum coating of workpieces, which
comprises
a conveyor device, and
at least one coating apparatus arranged on the conveyor
device, the coating apparatus being connected to at least two
feed lines via a valve block.
According to a refinement of the invention, the valves can be
switched or actuated in a freely selectable way. The compact
arrangement of the valves in or on a valve block reduces the
length of the supply passages required and therefore the
volume which has to be evacuated. Moreover, it is easy to
exchange wearing parts.
It is particularly preferable for the valve block, like the
coating apparatus, to be arranged, on the conveyor device.
This makes it possible to avoid moving couplings, which are
expensive and have an adverse effect on the conductance and
the leak rate.
A suitable coating apparatus in this context is in particular
a coating apparatus according to the invention as described
above, which comprises a reactor having a moving sleeve part
and a base element, as well as a device for introducing
electromagnetic energy into the at least one coating chamber,
with the reactor also having at least two coating places.
Of course, it is also possible for coating apparatuses of
other designs to be used for a coating installation according
to the invention.
Accordingly, a corresponding process for plasma coating
comprises the steps of
positioning at least one workpiece which is to be coated
at a coating place of a reactor of a coating station or
coating apparatus which is arranged on a conveyor device of a
coating installation,
evacuating the area surrounding a surface of the
workpiece which is to be coated,
supplying process gas, and
generating a plasma by the introduction of
electromagnetic energy, at least one of the steps of
evacuating or supplying process gas being controlled by
switching valves of a valve block which is arranged on the
conveyor device.
The plasma is in this case generated in particular in the
area surrounding the surface of the workpiece which is to be
coated, with the process gas being fed to the area
surrounding the surface.
According to one embodiment of the invention, a suitable
coating installation in general has a coating apparatus with
a reactor which comprises at least two chamber parts, at
least one of which parts is moveable, with a sealed coating
chamber being formed between the chamber parts in the
position in which the parts have been fitted together. The
workpiece is in this case first of all positioned at the
intended coating place and then the parts are fitted together
to form at least one coating chamber.
As in the embodiments described above, it is preferable for
the coating apparatus to have at least two coating chambers
in order to achieve an increased throughput and to improve
the economics of the coating installation.
In an embodiment of the invention of this type, it is
expedient if the valve block has at least one valve and/or a
valve seat and each of the chambers is connected to the valve
block via at least one supply passage with the valve or the
valve seat.
The supply passages may in this case advantageously be
arranged symmetrically with respect to the valve or the valve
seat, in order for the chambers to be supplied uniformly and
in this way, for example, to achieve equal pressures in the
chambers.
In an embodiment of the invention in which the coating
apparatus has a plurality of coating chambers, a valve block
in which supply passages for the chambers are assigned to at
least one common valve of the valve block, is also
particularly advantageous. This reduces the number of valves
required and as a result also results in better conductances.
Accordingly, in a process for coating workpieces using a
coating installation having a coating apparatus which has a
plurality of coating chambers, it is advantageously possible
for at least one of the steps of evacuating the area
surrounding a surface of the workpieces which is to be coated
in the coating chambers or of supplying process gas to the
coating chambers to be realized via at least one common valve
of the valve block.
According to a refinement of the invention, at least one of
the feed lines produces a connection to at least one pump
device, in order for the coating chambers or the area
surrounding the surface or surfaces of the workpieces which
is/are to be coated to be evacuated and/or for process gas to
be pumped out.
Moreover, an advantageous refinement of the invention
provides for the coating apparatus, as in the case of the
coating apparatus according to the invention described above,
to comprise a base element and a sleeve part which can move
with respect to this base element, with at least one coating
chamber being formed between these fitted-together parts. In
this embodiment, it is particularly advantageous if supply
lines or supply passages between the valve block and the
coating chamber are routed through the base element to the
coating chamber. This arrangement makes it possible to avoid
moving lines or seals between the valve block and the coating
chamber. According to a variant of this embodiment, the valve
block even forms a constituent part of the base element or of
a rigid part of the reactor, i.e. a part of the reactor which
does not move for opening and closing of the chamber. This
allows the lengths of the supply lines to be reduced to a
minimum.
Moreover, according to a further embodiment of the invention,
it is provided that the valve block has pneumatically or
electromagnetically switched valves.
A pneumatic distribution device may advantageously be
arranged on or integrated in the valve block, so that, for
example for pneumatically switched valves, only a single
compressed-air feed line is required.
The opening and closing of the pneumatically actuable valves
can be controlled in particular by the pneumatic distribution
device.
By suitable arrangement of the feed lines to the valve block,
the valves of the valve block can advantageously be assigned
to different operating media, such as for example pressure
sources; the term operating media or pressure sources is to
be understood in particular as meaning reduced-pressure
sources, such as for example suitable pump devices, excess.-
pressure sources, standard or ambient pressure sources and
gas sources, for example a process gas source. By switching
the valves, it is then possible for these pressure sources,
for example, to be sequentially connected to the coating
chamber and thereby switched on and off. These pressure
sources may, inter alia, comprise ambient pressure, various
levels of reduced pressure, and supply and extraction devices
for process gas.
The coating of workpieces in the form of hollow bodies, such
as for example, bottles is preferred. In this context, it is
advantageous if there are separate supply passages for the
interior of and the area surrounding such workpieces, the
supply passages being connected to at least one valve or
valve seat of the valve block. For example, the interior of
and the area surrounding the workpiece can be evacuated via
separate supply passages. This is advantageous inter alia if
only the inside is to be coated. In this case, the area
surrounding the workpiece only needs to be evacuated to a
sufficient extent for the pressure difference between the
interior and the surrounding area not to cause deformation of
the workpieces.
Furthermore the valve block can be designed in such a way
that it comprises at least part of a supply passage in which
a gas lance can be received. This supply passage may be
provided in particular for the purpose of supplying the
interior of workpieces in the form of hollow bodies. For the
purpose of internal coating, the interior of the workpiece
can be evacuated, the lance can be introduced into the
interior and process gas can be supplied through the lance.
To avoid expensive and vulnerable dynamic seals, a coating
installation in accordance with one embodiment of the
invention may have at least one pump device arranged on the
conveyor device. This allows the evacuation to be carried out
at least partially using at least one such pump device
arranged on the conveyor device, with the avoidance of moving
seals.
According to yet another embodiment of the invention,
consideration is given in particular to the coating apparatus
being conveyed on a circular path on the conveyor device.
Accordingly, the conveyor device of a coating installation
according to the invention may comprise a rotor, for example
a coating carousel ,or a plasma wheel. When the installation
is operating, therefore, the coating apparatus rotates on the

rotor, so that different circle sectors correspond to,
different process phases. This allows the installation to be
a particularly simple structure and also allows a simple
process sequence. In particular, it is also possible for a
plurality of coating apparatuses which, by way of example,
each comprise a coating apparatus according to the invention
as described above, to be arranged on the rotor.
In the text which follows, the invention is described in more
detail on the basis of preferred embodiments and with
reference to the appended drawings, in which identical
reference numerals denote identical or similar parts. In the
accompanying drawings:
Fig. 1A shows a cross section through an embodiment of
the invention,
Fig. 1B shows a variant of the embodiment shown in
Fig. 1A with a single microwave head for supplying
the coating chambers together,
Fig. 2 shows a further variant of the embodiment
shown in Fig. 1A with a common coating chamber for
two coating places,
Fig. 3 shows a cross-sectional view through an
embodiment of the invention with the opening and
closing operation controlled by mechanical control
cams,
Fig. 4 shows a diagrammatic plan view of a coating
installation having a multiplicity of coating
apparatuses according to the invention,
Fig. 5 and
Fig. 6 show views of two exemplary embodiments of
coating installations according to the invention
with pump devices carried along by the conveyor
device,
Fig. 7 shows a cross-sectional view of an embodiment
of a valve block according to the invention for
controlling the supply to the coating chambers,
Fig. 8 shows a section on section line A-A in Fig. 7
perpendicular to the section plane illustrated in
Fig. 7,
Fig. 9 shows a section on section line B-B in Fig. 7
perpendicular to the section plane illustrated in
Fig. 7, and
Figs. 10A
and 10B show a sectional view and a plan view of a
sealing flange of a coating apparatus for
workpieces in the form of hollow bodies.
Fig. 1A shows a diagrammatic cross-sectional view through an
embodiment of the coating apparatus according to the
invention, which is denoted overall by reference numeral 1.
The coating apparatus 1 comprises a reactor 18 having a base
element 33, which in the present exemplary embodiment is in
the form of a base plate, and a moveable sleeve part 19, as
well as a device 2 for introducing electromagnetic energy.
The moveable sleeve part 19 may, for example, be in the form
of a cylindrical chamber wall.
In the fitted-together position, as illustrated in Fig. 1,
two sealed coating chambers 15, 17, which each constitute a
coating place 12 or 14, respectively, for a workpiece and
into which electromagnetic energy is introduced in order to
ignite the plasma for coating, are formed between sleeve part
19 and base element 33. Accordingly, in the embodiment shown
in Fig. 1, two workpieces can be treated simultaneously.
Separating the chambers prevents the plasmas from affecting
one another during the coating operation. The coating
chambers 15, 17 of the reactor 2 are sealed off from the
environment by seals 29 and 31 which are arranged between
base element 33 and sleeve part 19.
To coat workpieces 15 and 17, the workpieces are arranged on
the base element 33, then the sleeve part 19 is brought
together with the base element 33 by moving the sleeve part
19, so that in the fitted-together position of the two parts
sealed coating chambers 15, 17, in which the workpieces 25,
27 are located, are defined between sleeve part 19 and base
element 33. The coating chambers 15, 17 are then evacuated,
process gas is introduced, and finally a plasma is generated
by the introduction of electromagnetic energy, so that a CVD
coating is formed on those surfaces of the workpieces which
adjoin the plasma.
The device 2 for introducing electromagnetic energy also
comprises a device for generating electromagnetic energy from
two microwave heads or microwave generators 3 and 5, an
adaptor in the form of a rectangular waveguide 4 and two feed
lines or coupling channels 7 and 9 which branch off from the
rectangular waveguide and in the embodiment illustrated in
Fig. 1 are in the form of coaxial conductors. The microwave
heads preferably generate microwaves at the post office-
approved frequency 2.45 GHz.
A variant of the embodiment illustrated in Fig. 1A is shown
in Fig. 1B. This variant has only a single microwave head 3.
In this case, both coating chambers 15, 17 are connected to
the single microwave head. The microwave energy is then
distributed between the individual coating chambers 15, 17 by
means of an impedance structure or waveguide structure 10, as
described, for example, in the German patent application
bearing the application number 101 38 693.1-52.
In the embodiments illustrated in Figs. 1A and 1B, for the
coating chamber to be opened and closed, the sleeve part 19
is moved substantially perpendicular to the base element 33,
in the direction indicated by A. Direction A in this case
runs along the supply conductors 7 and 9, so that the sleeve
part can move along the supply conductors. The conductors in
this case simultaneously serve as a guide for the sleeve
part. To open and close the coating chambers 15, 17, the
sleeve part 19 is moved accordingly, whereas the base element
33 remains in a fixed position.
Furthermore, the sleeve part 19 has openings 6 and 8 in which
the supply conductors 7 and 9 of the device 2 for introducing
electromagnetic energy engage. The coaxial conductors or
supply conductors 7 and 9 are provided with sealing collars
71 and 91, which when the coating chambers 15, 17 are being
closed are pressed onto seals 21 and 23 which are arranged on
the sleeve part 19 and thereby close the coating chambers 15
and 17 in a vacuum-tight manner. Moreover, the coaxial
conductors 7, 9 are provided with dielectric windows 11 and
13, for example quartz glass windows for the microwaves to be
introduced into the low-pressure or vacuum range of the
reactor 18.
The embodiments shown in Figs. 1A and 1B are specifically
designed for the coating of workpieces 25 and 27 which are in
the form of hollow bodies; in Figs. 1A and 1B, bottles are
illustrated as suitable examples of the workpieces. The base
element 33 has sealing flanges 125 with seals 51 and 53
which, at the mouth opening of the workpieces, seal off the
interior of the workpieces 25 and 27 in the form of hollow
bodies in a vacuum-tight manner with respect to the
surrounding area. This allows different pressures to be set
inside and outside the workpiece, for example in order to
allow purely internal coating or also purely external coating
to be produced or to allow different coatings to be produced
in the interior and on the outer surface of the workpieces
25, 27.
Figs. 10A and 10B show a sectional illustration and a plan
view of a sealing flange for sealing the mouth opening of a
workpiece. The sealing flange has a first part 127 and a
second part 129, which are screwed together. The seal 51 is
clamped between these two parts 127, 129 as a result of them
being screwed together and is thereby fixed in place. Part
129 of the sealing flange is secured to the base 33 of a
coating apparatus 1 according to the invention. Part 127 has
an insertion opening 131 which widens in the direction
opposite to the insertion direction of the workpiece 25, in
order to facilitate introduction of the workpiece. The
internal diameter of the insertion opening 131 is smaller
than the internal diameter of the seal 51. When the workpiece
25, such as in particular a bottle, is being inserted,
therefore, mouth opening 26 of the workpiece comes into
contact with the seal 51. As a result of the workpiece 25
being pressed onto the seal 51 or onto the sealing flange
125, the interior is sealed off with respect to the area
surrounding the workpiece 25.
In many cases, a typical workpiece to be coated, such as for
example a plastic drinks bottle, does not have a particularly
planar mouth opening. This can lead to leaks if the seal is
insufficiently flexible. To improve the flexibility of the
seal 51, the part 129 for this purpose has an undercut 130 in
the form of an annular depression running around the inner
edge of the part 129. The seal 51 can yield in this region
and thereby match the shape of the mouth opening of the
workpiece 25.
Supply passages 46 which open out into the coating chambers
15, 17 of the coating places 12, 14 and are connected to a
gas supply (not shown) via a valve 74, can be provided for
the purpose of supplying the area surrounding the workpieces
in the coating chambers with process gas for external
coating. Then, after the coating chambers 15, 17 have been
evacuated, process gas can also be fed to the area
surrounding the workpieces via the passages 46 and an
external coating can also be realized by igniting a plasma in
this region.
To enable the coating chambers 15, 17 to be evacuated and
vented, supply passages 35, 37, 39, 41, 43 and 45 are
provided in the base element, the supply passages 43 and 45
serving as chamber connection passages and the supply
passages 35, 37 serving as workpiece connection passages.
Dynamic seals or moving feed lines are avoided by the supply
passages being arranged in the stationary part of the
reactor, specifically the base element 33. The supply
passages, 5, 37, 39, 41, 43 and 45 can in this case serve
both as evacuation passages for evacuation and discharging of
process gas, and as vent passages for venting the coating
chambers before the workpieces are removed.
To enable different pressures or gas atmospheres to be
produced in the interior of and the area surrounding the
workpieces, the base element has separate supply passages for
evacuation and venting for the interior 22, 24 of the
workpieces, on the one hand, and the area surrounding the
workpieces 25, 27 in the form of hollow bodies, on the other
hand. Specifically, the supply passages 43 and 45 serve to
evacuate and vent the area surrounding the workpieces 15, 17
and the supply passages 37, 39 serve to evacuate and vent the
interior 22, 24 of the workpieces 15, 17.
Furthermore, the supply passages 43, 45 for the are a
surrounding the workpieces and the supply passages 37, 39 for
the interior of the workpieces for both coating places are in
each case connected to one another and open out into a common
supply passage 41 for the area surrounding the workpieces and
a supply passage 35 for the interiors 22, 24 of the
workpieces.
The process gas for the internal coating of the workpieces
25, 27 is supplied via hollow gas lances 55 and 57 which
project into the interior of the workpieces during the
coating operation. In the embodiment illustrated in Fig. 1A,
these gas lances are sealed off from the environment of the
coating apparatus 1 by means of dynamic seals 47 and 4 9
arranged on the base element 33. The flow of process gas is
switched on and off by a process gas valve 60. The valve 60
can also be designed as a control valve for continuously
controlling the process gas flow.
As an alternative to what is illustrated in Figs. 1A and 1B,
the coating apparatus 1 and/or the valve block 100 may also
have a plurality of process gas valves, for example a primary
process gas valve and a secondary process gas valve.
Different process gases can then be admitted or individual
process gas components supplied through the individual
valves, in order to allow the composition of the coating
which is deposited to be adapted. In this way, it is
advantageously possible, for example, to deposit multilayer
coatings with individual layers of different compositions on
the workpieces. It may, inter alia, be advantageous first of
all to apply a bonding layer and then a barrier layer, in
order to increase the durability of the coating and to
prevent it from becoming detached.
In the embodiment of the apparatus according to the invention
illustrated in Fig. 1B, the seals 47, 49 are secured to the
gas lances 55, 57 and the sealing rings of the seals 47, 49
are arranged axially, so that the gas lance does not rub
against the sealing ring when it is being moved in and out.
Accordingly, in this case there is no dynamic sealing, but
rather the sealing ring forms a seal, as the gas lance is
introduced when pressure is exerted on it in the extended
position of the gas lances.
Moreover, pump devices 63, 65 and 67 are connected, via
valves 62, 64 and 66, to the feed passage 35 for evacuating
the interiors 22, 24 of the workpieces 25, 27. The pump
device 63 serves to discharge process gas, and the valve 62
correspondingly serves as a process vacuum valve. The valves
64 and 66 serve as secondary and primary vacuum valves which
are opened and closed sequentially in order to evacuate the
coating chambers and/or the interiors of the workpieces in
the form of hollow bodies, in order to realize evacuation in
several pressure stages. The pump devices 65 and 67 are
intended for evacuation to the residual gas pressure required
for coating, it being possible for the pump devices to reach
different end pressures and to be successively switched on
and off for evacuation and discharging of process gas, so
that a multi-stage pump system is created. Of course,
however, it is also possible to use single-stage pump systems
or systems with even more stages. The first pump stage, using
the pump device 67, can advantageously be designed for
evacuation from atmospheric pressure down to approximately 50
mbar. This can be followed, as a further pump stage by means
of the pump device 65, by evacuation from the pressure
reached by the first pump stage to the base pressure, which
is typically in a range between 0.05 and 0.8 mbar.
Alternatively, in particular if only internal coating of the
workpieces is to be carried out, the interior 22, 24 of the
workpieces 15, 17 can be evacuated to a base pressure of
be evacuated to a fixed external pressure of between 1 and
100 mbar. This means that the base pressure does not have to
be reached on the outside. Consequently, inter alia it is
possible to shorten the pumping time by reducing the pumped
volume after the external pressure level has been reached,
since from this point on only the interior has to be
evacuated further. The evacuation from the preliminary vacuum
in the range from 10 mbar to 100 mbar down to the base
pressure may advantageously also, in accordance with a
further exemplary embodiment, be carried out using further
pump devices and valves (not shown in Figs. 1A and 1B) in
narrower steps or pressure stages.
Finally, process gas which flows in is pumped out by a third
pump stage using the pump device 63, resulting in the process
gas being exchanged and the pressure in the coating chambers
being stabilized.
Furthermore, the supply passage 41 is connected to the supply
passage 35 via a bypass line 75 which is switched by a valve
73 serving as a chamber vacuum valve. The areas surrounding
the workpieces in the coating chambers 15, 17 can also be
evacuated in this way. For this purpose, during the
evacuation operation, the bypass line 75 is opened by means
of the valve 73, so that the pump devices 65 and 67 are
connected to the supply passages 43 and 45 via this line.
After the evacuation has been concluded, the valves 73, 66
and 64 are then closed and process gas, after the valve 60
has been opened, flows via the lances 55, 57 into the
interiors of the workpieces, and after the process vacuum
valve 62 has been opened is continuously pumped out by the
pump device 63. Furthermore, after the plasma has been
ignited, fresh gas constantly flows in via the gas lances 55
and 57 and/or the passages 46, and consumed gas and residues
of unconsumed process gas are pumped out by the pump device
63 via the opened valve 62.
After coating has finished, it is then possible, by opening
the valves 61 and 77, to vent both the interiors and the
surrounding coating chambers 15, 17. Standard pressure then
prevails in the coating chambers and the workpieces, and the
reactor can be opened without the need for much force. Valve
61 serves as workpiece vent valve and valve 77 serves as
chamber vent valve.
According to an advantageous refinement of the invention, the
valves 60, 61, 62, 64, 66, 73, 74, 77 are combined in a valve
block 100 which, like the coating apparatus 1, is arranged on
a conveyor device (not shown in Figs. 1A and 1B) of a coating
installation. Via the valve block 100, the coating chambers
15, 17 of the coating apparatus 1 are connected to the feed
lines to the pump devices 63, 65, 67, and via the valve 650
to a process gas source, and via the valve 77 to venting with
ambient pressure.
According to a refinement of the invention, the valve block
100 furthermore has a pneumatic distribution device 103 as
diagrammatically depicted in Fig. 1A. This device distributes
compressed air from a compressed-air feed line 105 via
distribution lines 106 to the individual valves. The
exemplary embodiments explained in Fig. 1B and the following
figures may also have a pneumatic distribution device 103 of
this type, but such a device is not shown in those figures
for the sake of simplicity.
Fig. 2 illustrates a variant of the embodiment shown in
Fig. 1. In this variant, unlike in the embodiment described
with reference to Fig. 1, there is a common coating chamber
15 for two coating places 12 and 14. For this purpose, the
sleeve part 19 does not have two separate sleeves, as in the
exemplary embodiment described above, but rather one common
sleeve which fits over both workpieces or over both coating
places when it is closed. Accordingly, the coating apparatus
also requires only one supply passage 41 for the evacuation
and venting of the reactor chamber or coating chamber 15.
Fig. 3 illustrates a cross-sectional view through an
embodiment of the invention in which the opening and closing
of the coating chambers is effected by mechanical control
cams. For the sake of clarity, the feed passages and the
pumps and control valves are not illustrated in Fig. 3.
There is an arm 81 at the sleeve part 19 of the coating
apparatus 1. Cam rollers 84, 85 and 86 are arranged at the
arm 81. The cam rollers 84, 85 and 86 engage around a
mechanical control cam 80 past which the coating apparatus 1
is moved in the conveying direction. The control cam 8 0
likewise extends along the conveying direction and is
suitably curved, so that its cross-sectional profile extends
along direction A. As a result, when the coating apparatus
moves past the control cam, the arm and the sleeve part 19
connected to it likewise move along the direction A, with the
result that the coating chambers are opened and closed in
order for workpieces to be inserted into the coating places
12 and 14 or to be removed.
The movement of the gas lances 55 and 57 can be controlled in
the same way. For this purpose, the gas lances are secured to
a carrier 78, to which an arm 83 is also fitted. The arm 83
is once again provided with cam rollers 87, 88 and 98, which
engage around a further mechanical control cam 82. The gas
lances are moved in a similar way to that which has been
described above with regard to the movement of the sleeve
part 19. The passages in the base element 33, within which
the gas lances 55 and 57 move, are sealed in a gas-tight
manner with respect to atmosphere by dynamic seals 47 and 49
with a leak rate of
of the leak rate it is impossible for any gas to enter the
interior of the workpieces 25 and 27 in the form of hollow
bodies from the environment. As an alternative to what is
illustrated in Fig. 3, it is also possible to use non-dynamic
seals 47, 49 which are secured to the gas lances 55, 57 and
have an axial sealing ring, as described with reference to
Fig. 1B.
Fig. 4 illustrates a diagrammatic plan view of a coating
installation 90 for coating workpieces 25 which is equipped
with a multiplicity of coating apparatuses 1 according to the
invention. The coating installation 90 comprises a rotary
conveyor device or a rotor 91, on which, by way of example,
12 of the coating apparatuses 1 according to the invention
are arranged. Furthermore, the coating installation comprises
a control cam 80 mounted in a fixed position for controlling
the opening and closing operations of the coating device 1.
Moreover, the coating devices 1 each have arms 81 which, as
has been illustrated with reference to Fig. 3, are secured to
the respective sleeve parts of the reactors and are moved by
being moved past the control cam 80.
The workpieces 25 are fed via a conveyor rail 94 to an
allocation wheel or transfer wheel 92, which then transports
the workpieces to the coating places of the coating
apparatuses 1. The workpieces are then fixed in suitable
receiving parts of the coating places of the coating
apparatuses 1. When the rotor rotates, the sleeve parts are
closed by being moved past the control cam 80 as described
above, and the coating chambers of the reactors are
evacuated. In the case of workpieces in the form of hollow
bodies, it is then possible for gas lances to be introduced
into the workpieces, likewise under the control of a control
cam. Then, process gas is admitted and the coating is
effected by the introduction of microwaves while the rotor 91
continues to rotate.
The supply of process gas, the venting and evacuation of the
coating chambers of the coating apparatuses 1 is controlled
by means of valve blocks 100 which, together with the coating
apparatuses, are arranged on the rotor and rotate with it. In
this embodiment of a coating installation 90, moreover, pump
devices 63, 65 are also arranged on the rotor so as to rotate
with it, and these pump devices are connected to the valve
blocks 100 for supplying vacuum to the coating chambers via
feed lines. In addition, there may also be one or more pump
devices which are arranged in a fixed position and are
connected to the valve blocks via a rotary feed.
An arrangement of this nature, with pump devices and valves
which rotate with the rotor, as has been explained in
principle with reference to Fig. 4, is also described in the
German patent application bearing application number
102 53 "512.4-45, the content of disclosure of which is hereby
also incorporated in its entirety by reference in the subject
matter of the present invention.
After the treatment of the workpieces has ended, the sleeve
parts of the coating apparatuses 1 are raised again by means
of the control cam 80, and the chambers opened, after which
the coated workpieces 25 are removed by a conveyor wheel 93
and fed to a transport rail 96 to be transported onward.
Fig. 5 and Fig. 6 illustrate views of two further exemplary
embodiments of coating installations 90 according to the
invention, in which pump devices 63, 65 are conveyed by the
conveyor device. In these exemplary embodiments too, the
conveyor device comprises a rotor 91 with coating apparatuses
1 arranged thereon. The valve blocks 100 are arranged in the
vicinity of the coating apparatuses 1. The coating devices 1
are connected to pump devices 63, 65, 67, 69 via the valve
blocks 100, the connection being effected via feed lines 119
from the valve block 100 to a ring distributor 120.
The pump devices 63 and 65 are arranged on the rotor 91 so as
to rotate with it, whereas the further pump devices 67, 69
are disposed in a fixed position. The connection to the fixed
pump devices 67, 69 is additionally effected via a rotary
feed 122.
The two exemplary embodiments shown in Figs. 5 and 6 differ
with regard to the arrangement of rotary feed and pump
devices. In the embodiment of a coating installation
according to the invention shown in Fig. 5, the pump devices
63 and 65 which rotate with the rotor are arranged above the
coating stations 1, and in the embodiment shown in Fig. 6
they are arranged beneath the coating stations 1. In both
exemplary embodiments, the rotary feed 122 is arranged
centrally on the axis of rotation 124, with the rotary feed
122 being arranged above the ring distributor 120 in the
exemplary embodiment shown in Fig. 5 and below the ring
distributor 120 in the exemplary embodiment shown in Fig. 6.
In these exemplary embodiments, the fixed pump devices 67, 69
serve as a preliminary stage to the pump devices which rotate
with the rotor and for higher pressure ranges in the case of
sequential evacuation of the coating chambers. The individual
pump devices are sequentially switched on and off in order to
evacuate and discharge process gas under the control of
valves of the valve blocks 100.
Fig. 7 shows a cross-sectional view through an embodiment of
a valve block 100 according to the invention for controlling
the supply to the coating chambers 15, 17 of a coating
apparatus 1 according to the invention or a coating
installation having coating apparatuses 1 of this type. The
sleeves of the coating apparatus 1 are not shown here, for
the sake of clarity. The valves of the valve block are also
only indicated diagrammatically,.
The embodiment illustrated here is advantageous in particular
for supplying two plasma or coating chambers 15, 17 with as
far as possible a symmetrical configuration of the respective
feed passages or supply passages. In a region of the valve
block 100 which faces the coating chambers, the valve 73, the
workpiece vent valve 61 and the chamber vent valve 77 are
arranged on a substantially identical vertical plane. The
primary vacuum valve 66, the secondary vacuum valve 64 and
the process vacuum valve 62 are arranged beneath this plane
and in a vertical direction beneath one another.
The valve block 100 illustrated in Fig. 7 is intended to
supply a coating apparatus 1 having base element 33 and
moveable sleeve part and having two coating chambers 15, 17,
as shown, for example, in Fig. 1A. A correspondingly designed
valve block 100, which is arranged on the conveyor device of
a coating installation 90, may, however, also be used for
other types of coating apparatuses conveyed by the conveyor
device. In general, for this purpose a suitable coating
apparatus has a reactor which comprises at least two chamber
parts, at least one of which chamber parts is moveable, with
at least one sealed coating chamber being formed between the
chamber parts in the fitted-together position of the parts.
The coating apparatus 1, which is not illustrated in full in
Fig. 7, is connected, via the valve block 100, to at least
two feed lines in order to supply the coating chambers 15, 17
with vacuum and process gas.
Unlike what is illustrated in Figs. 1A, 1B and 2, the supply
passages 37, 39 for the inner region of both coating places
do not open out into a common supply passage 35 for the
interiors 22, 24 of the workpieces. Rather, in this case the
supply passages 37, 39 are connected, via branches 110-115 in
the valve block 100, to the valves 62, 64, 66, which for
their part are connected to feed lines (not shown) to pump
devices 63, 65, 67.
Moreover, in the case of the valve block 100 illustrated in
Fig. 7, the supply passages 37 and 39 of the chambers are in
each case assigned to common valves 62, 64, 66, so that the
two coating chambers 15, 17 are supplied jointly via these
valves. It is also possible for the valves for supplying
process gas and for venting each to be assigned to both
coating chambers. As a result, at least one of the steps of
evacuating the area surrounding a surface of the workpieces
which is to be coated in the coating chambers 15, 17 or of
supplying process gas to the coating chambers 15, 17 can take
place via common valves 62, 64, 66 of the valve block 100.
The supply passages 37, 39 and branches 110-115 are,
moreover, arranged symmetrically with respect to the valves
62, 64, 66. This results in identical conductances of the
supply passages for both coating chambers 15, 17, so that
pressure differences between the two chambers 15, 17 are
largely avoided.
In the embodiment of the invention illustrated in Fig. 7, the
workpieces 25, 27 in the form of hollow bodies are also held
by holding elements 54, and to seal the interiors 22, 24
seals 51, 53 are pressed onto the mouth openings of the
workpieces 25, 27 by pistons.
The sectional illustration means that not all the valves of
the valve block can be seen in Fig. 7.
As a complementary measure, Fig. 8 shows a section on section
line A-A in Fig. 7, perpendicular to the section plane
illustrated in Fig. 7. The holding elements 54 are not
illustrated in Fig. 8, for the sake of simplicity. Fig. 8
shows the valve 73 which is connected to the supply passage
39 via a bypass line 75. The valve 73 connects the bypass
line 75 to the supply passage 43. A valve drive or actuating
element 102, which drives the valve 73 so as to switch it,
can also be seen. According to one embodiment of the
invention, the drive element is designed as a pneumatic
drive. The pneumatic drives of a plurality of valves can in
this case be controlled by means of a pneumatic distributor
(not shown).
By opening the valve 73, it is also possible, if one of the
valves 62, 64, 66 is opened simultaneously, to evacuate the
area surrounding the workpieces 25, 27 in the coating
chambers.
Fig. 9 shows a section on section line B-B in Fig. 7,
perpendicular to the section plane illustrated in Fig. 7.
The coating chambers are connected, via the valve block 100,
to feed lines 119, via which vacuum and process gas are
supplied to the coating chambers. The feed lines 119 are
connected to connection pieces 117 on the valve block 100 and
are fixed using hose clips 104. According to the present
exemplary embodiment, connecting lines in the form of
flexible hoses are provided as feed lines 119. It is also
possible for connection pipes to be used as feed lines 119.
WE CLAIM
1. A coating apparatus (1) for the plasma coating of workpieces (25, 27),
comprising:
- a reactor (18) with a sleeve part (19) and a base element (33),
with at least one sealed coating chamber (15, 17) being defined
between the sleeve part (19) and base element (33), the latter two
parts are in the fitted-together condition, and
- a device (2) for introducing electromagnetic energy into the at least
one coating chamber (15,17),
characterized in that
the reactor (18) has at least two coating places (12, 14), and in
that the sleeve part is moveable.
2. The coating apparatus (1) as claimed in claim 1, comprising a guide for a
substantially perpendicular movement of the sleeve part (9) with respect
to the base element (33) in order to open and close the coating chamber
(15,17).
3. The coating apparatus (1) as claimed in claim 1 or 2, wherein the base
element has supply passages (35, 37, 39, 41, 43, 45) for evacuating
and/or venting and/or supplying process gas.
4. The coating apparatus (1) as claimed in one of claims 1 to 3, wherein at
least two separate coating chambers (15, 17) are formed between the
sleeve part (19) and base element (33).
5. The coating apparatus (1) as claimed in one of claims 1 to 3, wherein a
common coating chamber (15, 17) for at least two coating places is
formed between the sleeve part (19) and base element (33).
6. The coating apparatus (1) as claimed in one of claims 1 to 5, wherein the
sleeve part (2) has at least one opening (6, 8) in which a supply
conductor (9, 7) of the device (2) for introducing electromagnetic energy
engages.
7. The coating apparatus (1) as claimed in claim 6, wherein the at least one
supply conductor comprises a waveguide and/or a coaxial conductor.
8. The coating apparatus (1) as claimed in claim 6 or 7, wherein the sleeve
part (2) can be moved along the at least one supply conductor in order to
open and close the coating chamber (15,17).
9. The coating apparatus (1) as claimed in one of claims 1 to 8, wherein the
device (2) for introducing electromagnetic energy comprises at least one
device for generating electromagnetic energy.
lO.The coating apparatus (1) as claimed in claim 9, wherein the device for
generating electromagnetic energy comprises at least one microwave
head (3, 5).
11.The coating apparatus as claimed in one of claims 1 to 10, wherein the
device (2) for introducing electromagnetic energy comprises at least one
device (10) for distributing the electromagnetic energy.
12.The coating apparatus (1) as claimed in claim 9, 10 or 11, wherein the
device for generating electromagnetic energy comprises a device fcr
generating pulsed electromagnetic energy.
13.The coating apparatus (1) as claimed in one of claims 1 to 12, wherein
the coating places (12,14) are designed to receive workpieces (12,14) in
the form of hollow bodies, in particular to receive bottles, ampoules,
spherical caps or light bulb bodies.
14. The coating apparatus (1) as claimed in claim 13, wherein the coating
places (12, 14) have seals (51, 53) for sealing off the interior (22, 24) of
the workpieces (25, 27) in the form of hollow bodies.
15.The coating apparatus (1) as claimed in claim 13 or 14, wherein the base
element has separate supply passages (35, 37, 39, 41, 43, 45) for
evacuating and/or venting and/or supplying process gas for the interior of
(22, 24) and the area surrounding the workpieces (25, 27) in the form of
hollow bodies.
16.The coating apparatus (1) as claimed in claim 15, wherein the supply
passages (37, 39, 43, 45) of two or more coating places (12, 14) are
connected to one another via common further supply passages (35,41) or
supply lines.
17.The coating apparatus (1) as claimed in one of claims 1 to 16, wherein
the supply of process gas to a coating chamber (15, 17) is realized via at
least one gas lance (55, 57).
18.The coating apparatus (1) as claimed in one of claims 1 to 17, wherein
the movement for opening and closing the sleeve part (19) and/or a gas
lance (55, 57) is imparted via mechanical control cams (80, 82).
19. A system (90) for vacuum coating of workpieces, which comprises
- a conveyor device (91), and
- at least one coating apparatus (1), in particular a coating apparatus
(1) as claimed in one of the preceding claims, arranged on the
conveyor device (91), wherein the coating apparatus (1) is
connected to at least two feed lines (119) via a valve block (100).
20. The system as claimed in claim 19, wherein the coating apparatus (1)
comprises a reactor (18) which has at least two chamber parts (19, 33),
at least one of which chamber parts (19, 33) is moveable, with at least
one sealed coating chamber (15, 17) being formed between the chamber
parts (19, 33) in the position in which the parts (19, 33) are fittd
together.
21.The system as claimed in one of the preceding claims, wherein the
coating apparatus (1) has at least two coating chambers (15,17).
22.The system as claimed in claim 21, wherein the valve block (100) has at
least one valve (60, 61, 62, 64, 66, 73, 77) or a valve seat, and each of
the chambers is connected to the valve block (100) via at least one supply
passage (35, 37, 39, 41, 43, 45, 46) with the valve (60, 61, 62, 64, 66,
73, 77) or the valve seat.
23.The system as claimed in claim 22, wherein the supply passages (35, 37,
39, 41, 43, 45, 46) are arranged symmetrically with respect to the valve
(60, 61, 62, 64, 66, 73, 77) or the valve seat.
24. The system as claimed in claim 21 or 22, wherein when the coating
apparatus (1) has a plurality of coating chambers (15, 17), the system
additionally comprises supply passages (35, 37, 39,41,43,45, 46) for the
chambers (15, 17), which are assigned to at least one common valve (60,
61, 62, 64, 66, 73, 77) of the valve block (100).
25. The system (90) as claimed in one of the preceding claims, wherein at
least one of the feed lines (119) produces a connection to at least one
pump devices (63, 65, 67).
26.The system (90) as claimed in one of the preceding claims, wherein the
valve block (100) is arranged on the conveyor device (91).
27. The system as claimed in one of the preceding claims, wherein the
coating apparatus (1) comprises a base element (33) and a sleeve part
(19) which can move with respect to this base element (33), and in which
at least one coating chamber (15,17) is formed between these two fitted-
together parts (19, 33), wherein supply passages between the valve block
(100) and the coating chamber (15, 17) are routed through the base
element (33) to the coating chamber (15,17).
28. The system as claimed in one of the preceding claims, wherein the valve
block (100) has pneumatically or electromagnetically switched valves.
29. The system as claimed in one of the preceding claims, comprising a
pneumatic distribution device arranged on or integrated in the valve block
(100).
30.The system as claimed in one of the preceding claims, wherein the valve
block (100) has valves which are assigned to different operating media.
31.The system as claimed in one of the preceding claims, comprising
separate supply passages (35, 37, 39, 41, 43, 45) for the interior of (22,
24) and the area surrounding workpieces (25, 27) which are in the form
of hollow bodies and are connected to at least one valve or valve seat of
the valve block.
32.The system as claimed in one of the preceding claims, comprising at least
one pump device (63, 65) arranged on the conveyor device.
33.The system as claimed in one of the preceding claims, wherein the
conveyor device comprises a rotor (91).
34. A process for the plasma coating of workpieces (25, 27) in a coating
apparatus (1) or a system, in particular as claimed in one of the preceding
claims, with a reactor (18) having a moveable sleeve part (19) and a base
element (33), the process comprising:
- arranging at least two workpieces (25, 27) which are to be coated
on the base element (33);
- bringing together the sleeve part (19) with the base element (33)
so that in the fitted-together condition at least one sealed coating
chamber (15, 17) is defined between the sleeve part (19) and base
element (33), in the coating chamber accommodating at least one
of the workpieces (25, 27);
- evacuating the coating chamber (15,17);
- introducing the process gas in or around the workpieces, and
- generating a plasma by the introduction of electromagnetic energy
into the coating chamber, characterized in that the sleeve part (19)
is brought together with the base part (33) by moving the sleeve
part.
35.The process as claimed in claim 34, wherein the sleeve part is moved
substantially perpendicular to the base element (33) in order to open and
close the coating chamber (15,17).
36.The process as claimed in claim 34 or 35, wherein the evacuation and/or
venting and/or the supply of process gas is effected through supply
passages (35, 37, 39,41,43,45) in the base element.
37.The process as claimed in one of the preceding claims, wherein a pulsed
plasma is generated by the supply of pulsed electromagnetic energy.
38.The process as claimed in one of the preceding claims, wherein, to open
and close the coating chamber (15, 17), the sleeve part (2) is moved
along at least one supply conductor for supplying electromagnetic energy.
39.The process as claimed in one of the preceding claims, wherein when the
coatable workpiece is in the form of a hollow body, the area surrounding
the workpieces and the interior of the workpieces are evacuated
separately.
40.The process as claimed in one of the preceding claims, wherein when the
coatable workpiece is in the form of hollow bodies, the process gas is
introduced into the interior (22, 24) of the workpieces (25, 27).
41.The process as claimed in one of the preceding claims, wherein the
evacuation of the coating chamber is carried out in stages in at least two
pressure stages.
42.The process as claimed in one of the preceding claims, wherein when the
coatable workpieces (25, 27) are in the form of hollow bodies, in order to
evacuate the coating chamber (15, 17) the interior of the workpieces (22,
24) is evacuated down to a base pressure of
surrounding the workpieces (15, 17) is evacuated to the base pressure or
to a fixed external pressure of between 1 and 100 mbar.
43.The process as claimed in one of the preceding claims, wherein process
gas is introduced into the coating chamber (15, 17) via at least one gas
lance (55, 57).
44.The process as claimed in one of the preceding claims, wherein the
introduction of electromagnetic energy comprises the introduction of
microwaves.
45.The process as claimed in one of the preceding claims, wherein the
movement of the sleeve part (19) is imparted via mechanical control cams
(80, 82).
46. A process for the plasma coating of workpieces, in particular as claimed in
one of the preceding claims, comprising the steps of
- positioning at least one workpiece which is to be coated at a
coating place of a reactor of a coating apparatus which is arranged
on a conveyor device of a coating system,
- evacuating the area surrounding a surface of the workpiece which
is to be coated,
- supplying process gas, and
- generating a plasma by the introduction of electromagnetic energy,
at least one of the steps of evacuating or supplying process gas
being controlled by switching valves of a valve block which is
arranged on the conveyor device.
47.The process as claimed in claim 46, wherein the coating apparatus has a
reactor which comprises at least two chamber parts, at least one of which
parts is moveable, and wherein after the workpiece has been positioned at
a coating place, the at least two chambers parts of the reactor are fitted
together to form a coating chamber.
48.The process as claimed in either of claims 46 and 47, wherein the valves
are pneumatically actuated.
49.The process as claimed in claim 48, wherein the opening and closing of
the valves is controlled by a pneumatic distribution device.
50.The process as claimed in one of claims 46 to 49, wherein different
pressure sources are sequentially connected to the coating chamber by
switching the valves of the valve block.
51.The process as claimed in one of claims 46 to 50, wherein the workpieces
in the form of a hollow body is coated, and wherein the interior of and the
area surrounding the workpiece are evacuated via separate supply
passages (35, 37, 39,41,43,45).
52.The process as claimed in one of claims 46 to 51, wherein the coating
apparatus has a plurality of coating chamber, and wherein at least one of
the steps of evacuating the area surrounding a surface of the coatbale
workpices, or of supplying process gas to the coating chambers takes
place via at least one common valve of the valve block.
53.The process as claimed in one of claims 46 to 52, wherein the evacuating
is at least in part carried out by means of at least one pump device (63,
65) arranged on the conveyor device,.
54.The process as claimed in one of claims 46 to 53, wherein the coating
apparatus (1) is conveyed on a circular path on the conveyor device (91).

The invention relates to a coating apparatus (1) for the plasma coating of
workpieces (25, 27), comprising a reactor (18) with a sleeve part (19) and a
base element (33), with at least one sealed coating chamber (15, 17) being
defined between the sleeve part (19) and base element (33), the latter two parts
are in the fitted-together condition, and a device (2) for introducing
electromagnetic energy into the at least one coating chamber (15, 17). The
reactor (18) has at least two coating places (12, 14), and in that the sleeve part
is moveable.